They don't fly the CRJ-700. They fly the CRJ-705, which is basically a CRJ-900 with fewer seats, to meet scope clauses.
Totally lapsed when I put -700, I knew they don't have any.
The CSeries is replacing the E190 and the A319 ... roughly 45 frames. (With a few extra). The 737s are replacing the A320s and A321s.
If any of the CSeries options are exercised, then that will certainly be expansion.
Well to be exact, 43 frames, but yeah you're right there isn't much room. But going by the article, its promising that they'll take some, if not most, of their 30 options, and I based my thoughts around taking in some of those options.
I'm not sure it will really be all about YYZ with this plane. The CS3 has the right size to make a number of routes work out of YUL or YVR that wouldn't work on 320s or 737s. I'd therefore guess the bulk will be based out of YUL/YVR and the remaining in YYZ to operate long and thin markets that wouldn't work on anything else.
Yeah I can see a lot of YUL and YVR (they've showed both more interest than usual lately), but maybe some thinner sun destinations and some airports in the US that have limited connecting options to Europe/Asia may work too from YYZ. But if I were them, yeah I'd go to YUL and YVR first, a bunch of untapped potential in both. The link specifically mentions YVR-BOS as a good possibility.